Hearing aids are typically built with an external rotary control knob that enables the wearer of a hearing aid to adjust the amplification of the aid and thus the level of sound presented to the ear of the wearer. This adjusting capability allows the wearer to compensate for change in the performance of the aid or the momentary preference of the wearer. A readjustment is generally required upon installation of a hearing aid, or after any inadvertent displacement of the control knob, or when using a telephone, or after reduction of amplification effectuated during a rest period.
With present day techniques, the wearer lacks a reliable acoustic standard or reference to which amplification of the hearing aid can be adjusted. Further, no calibrated source is available which indicates both over-amplification as well as under-amplification. Commonly used acoustic quasi-type standards or references are radio and television sets, for example. In a social gathering, the voices of members of the group may be used as a reference. Such sounds do not provide a reliable calibrated acoustic reference for an individual hearing aid wearer nor a reference with parameters specific to the user.
Audiometers are used by trained technicians at a business location to determine the parameters of the hearing aids that are required to compensate for hearing impairment. The data obtained by an audiometer is the threshold of detection of the hearer at selected frequencies throughout the audio frequency spectrum. They cannot be used for a sound intensity standard by an untrained hearing aid wearer.
Advances in microelectronics have led to advances in audiometer systems and in digital automated systems which may be used with audiometers. Examples of such audiometer systems are described in U.S. Pat. Nos. 4,471,171-Kopke et al; 4,489,610-Slavin et al; and 4,548,082-Engbretson et al.
Audiometer systems have been used to obtain appropriate parameter settings, including audio gain of hearing aids. However, these prior art systems require operation by a trained technician and are expensive to make and maintain. Furthermore, use of an audiometer system is restricted to the place of business of the technician. Audiometers so used have controlled variable outputs which permit the technician to determine hearing aid parameters for a broad spectrum of hearing impairments. The device described herein has output parameters set by the audiologist to provide a volume control standard for a given individual.